The effects of fluoride will be studied in a number of systems. The injection of fluoride into rats causes a hyperglycemia which is the result of an enhanced rate of glycogenolysis. The basis for this increase has not been determined, and this will be studied during the next year. Initially the effects of an in vivo injection of fluoride on liver phosphorylase will be determined. Avian species are very resistant to the effects of fluoride ingestion and we have shown that this is not related to an inability to absorb fluoride from the gut. During the next year, we will determine if the basis for the resistance of chicks to fluoride is an inability of fluoride to enter cells in this species or if metabolic differences are involved. Fluoride has been claimed to be essential for reproduction in the mouse. Our experiments have failed to confirm these reports, and these studies will continue. A severe anemia has been reported in the studies where fluoride was a factor in reproduction, and the interrelationship between fluoride, iron, and copper metabolism will be studied.